Stubbed implementation of VK_GOOGLE_display_timing extension.

This provides the header changes and most of the "boilerplate" changes to add
the VK_GOOGLE_display_timing extension to Vulkan.  Future changes will modify
and integrate with the Surface, FrameEvents, and SurfaceFlinger code.

Test: Manually tested that existing apps won't tickle the new-extension paths.

Change-Id: Iec46b1cab4b2561702ebac9a4ae7587584793192